This invention relates to gas pumps of the type known as liquid ring pumps, and more particularly to liquid ring pumps for compressing gases to pressures above atmospheric pressure.
The typical liquid ring vacuum pump has one intake and one compression stroke per cycle. This is a so-called single-lobe pump. The asymmetrical construction of a single-lobe pump is acceptable in a liquid ring vacuum pump which is generally limited to a pressure differential across the pump of 15 to 20 p.s.i.g. Liquid ring compressors (i.e., liquid ring pumps used to compress gases to superatmospheric pressure) are, however, capable of achieving pressure differentials substantially greater than 15 to 20 p.s.i.g. Above about 25 p.s.i.g. the asymmetrical design of single-lobe pumps becomes a significant problem due to the practical limits imposed by rotor shaft stress and deflection caused by unbalanced forces in the pump. Accordingly, liquid ring compressors for providing pressure differentials above about 25 p.s.i.g. typically have a balanced double-lobe design (i.e., two intake and two compression strokes per cycle) which significantly reduces force imbalances acting on the shaft.
Heretofore the substantially different designs of liquid ring vacuum pumps and high pressure liquid ring compressors have generally precluded the design of common parts useful in both vacuum pumps and compressors. This effectively increases the cost of both the vacuum pumps and the compressors. In addition, the double-lobe design of high pressure liquid ring compressors has previously necessitated the use of complex, multi-passage heads to accommodate the dual intake and dual discharge passages of such compressors. This has increased the complexity and cost of high pressure liquid ring compressors.
In view of the foregoing, it is an object of this invention to provide liquid ring compressors which can have a substantial number of parts in common with liquid ring vacuum pumps.
Another object of this invention is to provide less complex and less costly double-lobe liquid ring compressors.
Still another object of this invention is to provide lower cost double-lobe liquid ring compressors which can have a substantial number of parts in common with single-lobe liquid ring vacuum pumps.